Hydraulic starter



Aug. 14, 1945. H. MLLY 2,382,437

HYDRAULI C S TARTER Iulg. M, 1945. H. MoLLY 2,382,437

HYDRAULIC STARTER Fliled Aug. lO, 1940 3 Sheets-Sheet 2 HMM@ Aug. i4, 1945. H. MOLLY 2,382,437

HYDRAULI C STARTER Filed Aug. l0, 1940 5 Sheets-Sheet 3 70 JI 74 11 12 l 13 f u l .f l 20 5 l Fl'g.

//7Veno/': 11k/may y WVM Patented Aug. 14, 1945 HYDRAULIC STARTER Hans Molly, Berlin-Tempelhof, Germany; vested in the Alien Property Custodian Application August 10, 1940, Serial No. 352,145 In Germany August 12, 1939 2 Claims. (Cl. 103-162) The present invention relates to a hydraulic device for starting engines, more particularly internal combustion engines. It is a well known fact that the torque required to move or force an engine out of its state of rest must have a value several times greater than the torque required to carry on the pickup movement'l or acceleration of the engine. If the starting is effected by means of a hydraulic device, a high pressure corresponding to a high torque isv required in the first instance which may be lessened, as soon as the engine has picked up speed. According to the invention it is proposed to feed the hydraulic motor serving to drive the starting device from a pump with an increasing volume delivery during the period of starting. Such pumps are known as radial piston pumps and axial piston pumps. It is more advantageous to provide for automatic control of the stroke adjusting member of an axial piston pump to increase the volume of delivery.

In this way the high torque required for starting the engine may be obtained by means of a very vsmall electric motor serving to drive the pump. By providing a hydraulic pump with adjustable stroke it is possible to greatly multiply the torque exerted by the electric motor on the engine to be started. Hence it is not necessary to change the dimensions of the electric motor to take care of the starting torque of the engine.

For Obtaining automatic control of the stroke adjusting member it is advantageous to have an external force exert a rocking force, decreasing at increasing rocking angles, on the stroke adjusting member. Said force is balanced by a counteracting rocking moment produced by the pump pressure. The external force may be supplied by a spring having a variable lever arm or by a spring system with non-linear force-displacement characteristic. The counteracting rocking moment may be produced in a manner already known by having the stroke adjusting member rock about a pivot located outside the cylinder block axis, so that the pressures produced in the working cylinders will shift the stroke adjusting member into its zero position.

It is essential that the pump produces the full pressure requisite for starting the engine only when the driving motor of the pump has attained its full number oi revolutions or its requisite revolutionary speed and has stored up a certain rotary force to be supplied during the starting process. For this purpose a pressure storing arrangement may be inserted in the pressure conduit of the pump to be charged during the starting period of the pump drive thereby retarding the attainment of the maximum pump pressure. It is advantageous to increase the retardation and to reduce the pressure from the storing apparatus, respectively, by taking care that the delivery is as small as possible during the starting period of the pump drive. This may be achieved by a pressure storage tank having a uid flow connection to a cylinder with a piston therein and spring means active between the piston and the stroke adjusting means. A further step in this direction might consist in having the stroke adjusting member retained in a slightly deflected position during the piston movement by means of a locking device capable of being released by the piston.

In this arrangement the pump in the first instance at a small stroke delivers relatively small amounts for storage in the storing arrangement. In this way the storage means removes any operative force from acting upon the piston until sufiicient time is afforded for the driving motor of the pump to attain its full revolutionary speed. Only then the stroke adjusting member of the pump is released and subjected to spring pressure, so that the pressure no'w may be increased up to a. maximum determined by the spring. This maximum pressure suiilces for starting the engine in question. As soon as the engine is in motion, the pressure is diminished which results in a further deection of the stroke adjusting member. Further possibilities of retarding the pressure increase during the starting period are afforded, if the external force acting on the adjusting member is released when a predetermined revolutionary speed of the pump driving gear has been reached.

This may be achieved in such a manner that a centrifugal pendulum coupled with the pump driving gear expands a spring exerting a rocking moment on the stroke adjusting member. Here also a, locking device capable of being released by the centrifugal pendulum may be provided, said spring in the iirst instance keeping the stroke adjusting member in the zero position.

It is likewise possible to have the centrifugal pendulum act directly on the stroke adjusting member, in which case, however, the point of application of the force would have to be chosen in such manner that a rocking moment, decreasing as the rocking angle increases, acts on the stroke adjusting member. In order to obtain the desired retardation during the starting period, the said member may be restrained in its zero position by a tension to be overcome by the centrifugal pendulum at a certain revolutionary speed of the driving gear.

'Ihe driving motor for the pump may be advantageously coupled with a movable mass in order to store up energy,

The invention is illustrated in detail by a number of embodiments shown schematically.

Fig. 1 is a diagrammatic sectional view showing a starting device in which the rocking moment is exerted on. the stroke adjusting member by means of a pressure cylinder connected to the 2 consumption conduit, said cylinder having a piston moving therein which contracts .a spring.

Figs. 2 and 3 are side elevations "showing starting devices in which the rocking moment is produced by means of a centrifugal regulator. In all figures similar reference characters designate corresponding parts.

In Fig. 1 the reference Vnumeral I denotes an electric motor whose rotor 2 is coupled with a driving flange 4 of an axial piston pump l by a shaft 3. The shaft 3 of the electric motor I is supported in a' casing 6 by means of ball bearings 1 and 3. A fly wheel 9 is rigidly connected on the shaft 3, said wheel being likewise enclosed in the motor casing. Piston rods I6 are articulately connected with the driving flange 4 of the axial piston pump 5,- and drive pistons II in cylindex-s I5. of block I2. The cylinder block I2 is supported in a swinging frame I3 at the point I4, so that, as already explained elsewhere, the

- pressure produced in the pump cylinders I5 tends to adjust the swinging frame I3 towards a stroke reduction of the pump 5. The control surface I6 of the cylinder block I2 is spherical and is guided by a ball I8 at the driving flange 4 by means of a centering member I1 capable of being longitudinally displaced within the cylinder block I2. The close contacting of the cylinder block I2 with the control surface. I6 is ensured by the action of a spring I9 upon the centering member If the cylinder block I2 is inclined relative to an axis of the driving flange 4, as shown in Fig. 1, the pistons I I move to and fro in the cylinders I5 and, by means of the conduit 20, will pump a certain amount of fluid into the motor 2i schematically represented as a starting motor, for instance, for a combustion engine. From this motor the fluid is carried back by means of a conduit 22 to a container 23, in which the entire pump 5 is likewise arranged. A conduit 24 branches off from the conduit 20, said conduit 24 leading on the one hand to a pressure storing arrangement 25 and on the other to a cylinder 26, in which a piston 21 is movably arranged. The piston 21, upon movement in the cylinder 26, strikes against a lug 28 of a lever supported at 29, which is acted upon by the tension of a spring 32 connected at 3| to the cylinder 26. In consequence of the lug 28 being struck by the piston, the lever 30 is rocked about the pivot 29 and releases a locking arrangement 33 so that the rocking frame I3 is free to swing the pump 5 through an angle amas.. This movement is likewise imparted by means of the piston 21, which contracts a spring 36 articulately connected with the rocking frame I3 and resting against the piston 21, said spring 36 being expanded andcontracted as a result of the movement of the piston 21 in the cylinder 26. The piston 21 in addition possesses a pin-like lengthening piece 34, the spring 36 being guided on said piece 34 as well as on a pin 35 mounted on the rocking frame I3. A stop 38 is provided to limit the adjustment of the rocking frame I3 in its initial position, i. e., at a certain angle of amm..

The illustrated starting device operates as follows: When the electric motor I is switched on lt begins to move slowly and sets the axial piston pump 5 connected with it in operation so as to deliver pressure fluid to the pressure storing arrangement 25 and the motor 2l, respectively, by means of the conduits 20 and 24. The pressure storing apparatus operates in such manner that the pressure in the conduits 20 and 24 in the rst asomar instance does not reach any high values, hence the motor I is not forced to exert any great force and is thus capable of reaching the desired number of revolutions or revolutionary speed within the starting period. When this point has been reached-provided the pressure storing apparatus possesses suitable dimensions-the condition will have been attained in which the pressure in the conduits 20 and 24 will increase considerably. As the pump 5 in the position illustrated operates through the angle amm., said position corresponding likewise to the initial position, a high pressure may be exerted by the pump through a small stroke. The pressure thus reached suillces to start the pressure fluid motor 2| coupled with the motor to be started. Almost simultaneously or even previously the piston 21 will have released the locking arrangement 33 by means of the lug 28 and the lever 30 so that the rocking frame I3 may be deflected due to the fact that the spring 36 had been placed under compression by the piston movement. This spring compression is opposed by a force produced by the excentric support of the rocking frame in the sense of a stroke reduction. As the pressure in the conduits 20 and 24 meanwhile has been reduced by the starting of the motor, the stroke reducing force is likewise diminished and the cylinder block carrier I3 is deflected further under the influence of the spring 36 until finally the angle amx. has been reached. Thus increasing pressure fluid quantities are being supplied to the motor 2l at decreasing pressure. The force necessary to achieve this is supplied by the motor I due to the fact that the swinging mass 9 bridges over the requisite high initial moment. When the motor has picked up, which should be the case at about the angle of amax. of the rocking frame, the pressure in the conduits 20, 24 reaches zero. The spring force, due to the backward stroke of the piston, is likewise reduced to zero and the rocking frame returns to its initial position.

The lever 30, which maintains the pump 5 with its projection in the angular position amm. may be dispensed with, without changing thereby the action of the starting device. -pump acted upon by the spring 36 will get to the position msx., as soon as the electromotor I has been set in operation. As in the first instance the conduits 20, 24 and the hydraulic accumulator 25 have to be filled up, the pump works in the beginning practically without any counter pressure and consequently there will not exist a moment, which will counterbalance the moment exerted by the spring 36. As soon however, as the conduits have been lled up and the pump builds up its delivery pressure the moment, which tends to deflect the cylinder block against the action of the spring 36 will increase. The cylinder block finally reaches again the position amm. From this position the above mentioned starting action will be repeated as illustrated in Fig. 1, i. e., at the beginning of the starting process the quantity of uid delivered to the motor 2 being small, at the same time the fluid pressure will be high. In the further phase of starting' however, i. e., when the countermoment exerted by the engine to be started decreases. the quantity of fluid being great and the pressure being low.

As shown in Fig. 2, centrifugal weights 4I, 42 are articulately connected at 40 to the shaft 3 of the electro-motor I by means of levers 43, 44 and levers 45, 46 with a sleeve 41 which is shiftable in the direction of the axis of the shaft 3 under the influence of the centrifugal weights 4I, 42.

In this case the` aaeaaer The sleeve 6l in turn is connected to a lever t3 swingably supported at d. A spring i! is articulately connected to the lever` i8 at the point 5I, the free end being connected at 52 with the rocking frame i3 of the pump 5. The spring 5G is tensioned upon displacement of the sleeve l, tending to rock the frame I3 upon its pivot id to increase the stroke of the pump. The articulate connection of the spring has been effected in such manner that the rocking moment produced by it is reduced at an increasing rocking angle.

The pump 5 in its initial position is restrained in the zero position by a lug 53. A rocking mo ment is not produced until a lever 54 having a secured on the lever 48, thus releasing stop 53. A spring 58 forces the lever 54 to contact the pin 58. The moment tending to decrease the stroke of the pump in the same way as shown in the embodiment according to Fig. 1` is effected through the excentric support of the rocking frame I3 about the axis I4. The conduit 20 again leads to a pressure duid motor which is suitably connected with the motor to be started. In all other respects the starting device of the construction shown in Fig. 2 corresponds to that of Fig. 1 with the exception that the pressure storing arrangement and the piston exerting the stroke increasing rocking moment on the rocking frame are omitted.

The illustrated starting device operates as follows: In its initial position the pump 5 is at the stroke position of zero. Hence it is possible for the motor I on having been switched on to reach its requisite number of revolutions without being submitted to any special load. Upon an increase of the revolutionary speed the centrifugal weights 6I, 42 will be forced to move outwardly thus tensioning the spring 5l) and the lever 54 actuated by the pin 55 will release the locking arrangement 53, 55, so that the pump 5 may be angularly derlected. Under the inuence of the pressure now produced in the conduit 25, the pump deiiects by small angles, at which high pressure suitable for eiiecting the starting oi the respective motor may be exerted at small strokes. This starting monient resulting from the high pressure, as shown above is bridged over by a fly wheel coupled with the motor i. As soon as the motor to be started has been set in motion, the pressure in the conduit 2b ialls oil with the result that the moment acting on the rocking frame I3 tending to decrease the stroke of the pump is likewise reduced. Due to the external force now exerted by the spring 50the frame I3 swings at greater angles. finally assuming the maximal stroke position when the motor has picked up, in which position large pressure iluid amounts are delivered. When the revolutionary speed of the motor I declines, the lever 48 again approaches its initial position, which results in a decreased tensioning of the spring 50 so that the pump 5 may also revert to its zero position, in which it may be aided by the force of a spring.

In Fig. 3 the centrifugal pendulum fonned by the weights 4i, 42 and the levers 43 to 46 direc-sly acts upon the rocking frame I3 at the stroke adjusting member by means of a lever system ad, 52 secured on the onehand at BI to lever i3 connected with the sleeve 41 and 0n "he other hand at the pivot 61. The pivots 5|, by which the rocking frame I3 is swingable are chosen so as te ensure that a rocking moment declining at increasing rocking angles acts on the stroke adjusting member. Here likewise it is of course necessary to eiect a retardation of the pressure increase during the starting period of the electro-motor i. In this instance it is eiiected in such a manner that the stroke adjusting member I3 is restrained in its zero position by a tension to be overcome by the centrifugal pendulum, as for instance in such a Way that the lever 48 is retained by a catch 63 swingably supported at 64 and acted upon by a spring B5. The operation of the device described should be apparent from the above description.

As mentioned in the beginning, the invention is not limited to the embodiments described. In addition to other obvious advantages, one principal advantage of the starting device consists therein that several motors may be started by means of but one pump, this being provided for several motors connected therewith for instance by a multi-way stop cock.

What is claimed is:

1. In a hydraulic pump of the piston type, the combination of a motor; a driving flange journaled for rotation about its axis and driven by said motor; a cylinder block hingedly mounted adjacent said flange, and provided with a plurality of bores; a piston in each of said bores; a rod for operatively connecting each piston with said ilange; a discharge conduit communicating with said bores; said ilange and said block being so arranged that swinging of said block about its mounting, causing inclination of the axis of the block relative to the axis of the flange, produces variations in the strokes of the pistons and consequent variations in the pressure of the uid discharged through said conduit, and said pressure tends to decrease said inclination; a stop to prevent decrease of said inclination below a predetermined minimum; a piston cylinder adjacent said block; a piston in said piston cylinder; a closed chamber adjacent said piston cylinder; a second conduit connecting said pump discharge conduit with said chamber and said piston cylinder; and a coil spring interposed between said` last mentioned piston and said block.

2. In a hydraulic pump of the piston type, the combination of a cylinder block formed with a plurality of cylinder bores, pistons in said cylinder bores, a driving ange mounted for rotation about its axis, means for rotating said flange, piston rods for operatively connecting said pistons with said driving flange, said cylinder block and said driving iiange being hingedly connected and so arranged as to allow for variations loi' the stroke of the pump in response to the inclination of one part relative to the other, and also so that the uid pressure of said pump tends to decrease such inclination and consequently decrease the stroke of the pump, a discharge conduit for said pump. a pressure storage means connected to said discharge conduit, a cylinder connected to said storage means, a piston in said cylinder responsive to the pressure in said discharge conduit, and a spring between said cylinder block and piston acting upon said cylinder block to increase said inclination and consequently increase the stroke of the pump, said spring being actuated by said piston.

HANS MOLLY. 

